Simplify the following expression: $a = \dfrac{4}{10x} - \dfrac{-2}{10x}$
Solution: Since the expressions have the same denominator we simply combine the numerators: $a = \dfrac{4 - (-2)}{10x}$ Combine like terms: $a = \dfrac{6}{10x}$ Simplify by dividing numerator and denominator by 2: $a = \dfrac{3}{5x}$